c++ - What is Implicit constructors on Java

Question

Is it mandatory to call base class constructor in Java? In C++ it was optional, so I am asking this.

When I extend ArrayAdapter, I get this error: "Implicit super constructor ArrayAdapter<String>() is undefined. Must explicitly invoke another constructor"

So, what is the purpose of calling base constructor? When I create object base class constructor will call & then it comes to derived right.

Answer 1

The no-args constructor is called implicitly if you don't call one yourself, which is invalid if that constructor doesn't exist. The reason it is required to call a super constructor is that the superclass usually has some state it expects to be in after being constructed, which may include private variables that can't be set in a sub-class. If you don't call the constructor, it would leave the object in a probably invalid state, which can cause all kinds of problems.